Tour: Exoplanets Need to be Prepared for Extreme Space Weather, Chandra Finds

Planets around other stars need to be prepared for extreme weather conditions, according to a new study from NASA’s Chandra X-ray Observatory and ESA’s XMM-Newton that examined the effects of X-rays on potential planets around the most common type of stars.

Astronomers found that only a planet with greenhouse gases in its atmosphere like Earth and at a relatively large distance away from its host star would have a chance to support life as we know it around a nearby star.

Wolf 359 is a red dwarf with a mass about a tenth that of the Sun. Red dwarf stars are the most common stars in the universe and live for billions of years, providing ample time for life to develop. At a distance of only 7.8 light-years away, Wolf 359 is also one of the closest stars to the Solar System.

The researchers think that Wolf 359 can help them unlock the secrets around stars and habitability because it is so close and belongs to such an important class of stars. Because red dwarfs are the most prevalent types of stars, astronomers have looked hard to find exoplanets around them. While some astronomers said they have evidence for two planets in orbit around Wolf 359 from optical telescopes, the jury is still out on those claims.

Regardless, even the possibility of planets around Wolf 359 is intriguing. Astronomers decided to use NASA’s Chandra X-ray Observatory and ESA’s XMM-Newton to see what the environment for any potential planets would be like there.

They found that Wolf 359 is producing enough damaging radiation that only a planet with greenhouse gases like carbon dioxide in its atmosphere — and located at a relatively large distance from the star — would likely be able to sustain life. The team looked at what astronomers call the “habitable zone,” the region around a star where liquid water could exist on a planet’s surface, for Wolf 359. They found that the output of high-energy radiation from Wolf 359 means that any planet located in the habitable zone around it is unlikely to have a significant atmosphere long enough for multicellular life, as we know it on Earth, to form and survive. That is, unless that planet is near the habitable zone's outer edge of a planet and has a significant greenhouse effect.

This result helps astronomers know not only where to look for habitable planets, but also what other factors may be necessary to study to understand where life may be possible beyond the Solar System.